of oestrich



UNITED STATES v Patented January 5, 1904.

PATENT OFFICE.

FRIEDRICH RIEOHE AND OTTO SAAME, OF OESTRIOH, GERMANY, ASSIGNORS TO THEFIRM OF RUDOLPH KOEPP (it 00., OF OESTRIOH, RHEINGAU,

GERMANY.

PROCESS OF MAKlNG OXALATES.

SPECIFICATION forming part of Letters Patent No. 748,791, dated January5, 1904.

Application filed May 9, 1903- Serial No. 156,489- (No specimens.)

To all whom it may concern:

Be it known that We, FRIEDRICH RIEGHE and OTTO SAAME, both subjects ofthe German Emperor, residing and having our postoffice address at 4.7Landstrasse,0estrich,Germany, have invented certain new and usefulImprovements in the Manufacture of Oxalates, of which the following is aspecification.

This invention relates to the preparation of oxalates by means offormiates.

Alkali formiates can by heating be converted into alkali oxalates,hydrogen being thereby liberated. (Merz and Wald, Berichte der Dent.O'he'm. Goa, 15, 1507.) This reaction gives good yields only when smallquantities are used, because in order to obtain good results it isnecessary to rapidly heat to about 420 centigrade, and the temperatureof 360 centigrade must be passed rapidly, and this is a great impedimentto the treatment of large quantities. Attempts have been made toovercome these difiiculties. a large quantity of an inert body, such ascarbonate of soda, be added to the formiate, (German patent No.111,078,) or even if sodium oxalate be employed, a sufficient yield ofoxalate is obtained without rapid heating; but the inert body must alsopass through the whole process.

We have found that an inert substance, whether soda or sodium oxalate,is not necessary to obtain a smooth reaction and a yield approximatingthe theoretical yield and that it is sufiicient that the reaction shouldbe carried out in the presence of a body that converts the formiate intoa thin liquid and also has a catalytic efiect which starts the liberation of hydrogen. We have found that free alkalies act in this manner.If the formiate be heated in the presence of a very small per centage offree alkali, the mass at a temperature below the melting-point of theformiate becomes a liquid practically as thin as water, the reactioncommencing at that temperature and once started proceeding smoothly andthere is no need to trouble about the temperature. It has already beenattempted to heat formiates in the presence of an alkali to transformthem into oxalates, (Dumas and Stass, Arm. d. Chem. Pharmaoie, 35-137Erlentory than with one per cent., and even less than that is sufficientto insure proper reaction.

In the process according to this invention the use of large quantitiesof inert substances in the presence of the formiate is avoided,

the reaction proceeds very smoothly and at a low temperature, and thereis no need to tronble about temperature. The final product is achemically -pure oxalate. Another great advantage of the said process isthat the formiates obtained by the usual process contain a quantity ofalkali sufficient for the process, and therefore can be at onceconverted into oxalates. The process may be conducted in either closedor open vessels and requires only apparatus of a simple character,occupying but little space, and there is considerable saving of fuel.

The following is an example of how the invention may be practicallycarried out; but the invention is not limited to the precise details ofthis example.

Ten kilograms of sodium formiate and one hundred grains of caustic sodaare heated in an open vessel. The mass melts, and at about 290centigrade hydrogen is briskly and uniformly evolved. The liquid becomesreadily solidified-as oxalate is formed, and when the temperature isabout 360 centigrade the vessel contains chemically-pure, porous, and

white oxalate. The reaction takes place so rapidly that stirring is notabsolutely necessary, and the operation is completed in about half anhour. 1

Instead of the alkali mentioned other bodies which will act in smallquantities on the formiates and convert them into thin liquid or act asa flux while hydrogen is evolved may be used.

Instead of free alkali a compound may be added which at about 300centigrade yields free alkali. Owing to the small amount of alkali, andconsequently of such compound, re-

5 quired in the process, the impurities present in the final productwill be so small as not to be objectionable.

We claim- The herein-described process of manufac- IO turin g oxalatesby means of formiates by heating the latter in the presence of a smallquantity of a free alkali not exceeding five per cent. as and. for thepurpose set forth.

In testimony whereof We have signed our names to this specification inthe presence of I two subscribing Witnesses.

FRIEDRICH RIEOHE.

OTTO SAAME.

Witnesses FRANZ HASSLAOHER, MICHAEL VoLK.

